MBlock.c 8.99 KB
Newer Older
1
/* -----------------------------------------------------------------------------
2
 * $Id: MBlock.c,v 1.30 2002/10/21 11:38:53 simonmar Exp $
3
4
 *
 * (c) The GHC Team 1998-1999
5
6
7
8
9
10
11
 *
 * MegaBlock Allocator Interface.  This file contains all the dirty
 * architecture-dependent hackery required to get a chunk of aligned
 * memory from the operating system.
 *
 * ---------------------------------------------------------------------------*/

12
13
/* This is non-posix compliant. */
/* #include "PosixSource.h" */
14
15
16
17
18
19
20

#include "Rts.h"
#include "RtsUtils.h"
#include "RtsFlags.h"
#include "MBlock.h"
#include "BlockAlloc.h"

21
22
23
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
24
25
26
27
28
29
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
sof's avatar
sof committed
30
31
32
33
#ifndef mingw32_TARGET_OS
# ifdef HAVE_SYS_MMAN_H
# include <sys/mman.h>
# endif
34
35
36
37
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
sof's avatar
sof committed
38
#if HAVE_WINDOWS_H
39
40
41
#include <windows.h>
#endif

42
43
#include <errno.h>

44
45
lnat mblocks_allocated = 0;

46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
/* -----------------------------------------------------------------------------
   The MBlock Map: provides our implementation of HEAP_ALLOCED()
   -------------------------------------------------------------------------- */

StgWord8 mblock_map[4096]; // initially all zeros

static void
mblockIsHeap (void *p)
{
    mblock_map[((StgWord)p & ~MBLOCK_MASK) >> MBLOCK_SHIFT] = 1;
}

/* -----------------------------------------------------------------------------
   Allocate new mblock(s)
   -------------------------------------------------------------------------- */

62
63
64
65
66
67
void *
getMBlock(void)
{
  return getMBlocks(1);
}

68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
/* -----------------------------------------------------------------------------
   The mmap() method

   On Unix-like systems, we use mmap() to allocate our memory.  We
   want memory in chunks of MBLOCK_SIZE, and aligned on an MBLOCK_SIZE
   boundary.  The mmap() interface doesn't give us this level of
   control, so we have to use some heuristics.

   In the general case, if we want a block of n megablocks, then we
   allocate n+1 and trim off the slop from either side (using
   munmap()) to get an aligned chunk of size n.  However, the next
   time we'll try to allocate directly after the previously allocated
   chunk, on the grounds that this is aligned and likely to be free.
   If it turns out that we were wrong, we have to munmap() and try
   again using the general method.
   -------------------------------------------------------------------------- */

sof's avatar
sof committed
85
#if !defined(mingw32_TARGET_OS) && !defined(cygwin32_TARGET_OS)
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

// A wrapper around mmap(), to abstract away from OS differences in
// the mmap() interface.

static void *
my_mmap (void *addr, int size)
{
    void *ret;

#ifdef solaris2_TARGET_OS
    { 
	int fd = open("/dev/zero",O_RDONLY);
	ret = mmap(addr, size, PROT_READ | PROT_WRITE, 
		   MAP_FIXED | MAP_PRIVATE, fd, 0);
	close(fd);
    }
#elif hpux_TARGET_OS
    ret = mmap(addr, size, PROT_READ | PROT_WRITE, 
	       MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
#elif darwin_TARGET_OS
    ret = mmap(addr, size, PROT_READ | PROT_WRITE, 
	       MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
#else
    ret = mmap(addr, size, PROT_READ | PROT_WRITE, 
	       MAP_ANON | MAP_PRIVATE, -1, 0);
#endif

    return ret;
}    

// Implements the general case: allocate a chunk of memory of 'size'
// mblocks.

static void *
gen_map_mblocks (int size)
{
    int slop;
    void *ret;

    // Try to map a larger block, and take the aligned portion from
    // it (unmap the rest).
    size += MBLOCK_SIZE;
    ret = my_mmap(0, size);
    if (ret == (void *)-1) {
	barf("gen_map_mblocks: mmap failed");
    }
    
    // unmap the slop bits around the chunk we allocated
    slop = (W_)ret & MBLOCK_MASK;
	
    if (munmap(ret, MBLOCK_SIZE - slop) == -1) {
	barf("gen_map_mblocks: munmap failed");
    }
    if (slop > 0 && munmap(ret+size-slop, slop) == -1) {
	barf("gen_map_mblocks: munmap failed");
    }
    
    // next time, try after the block we just got.
    ret += MBLOCK_SIZE - slop;
    return ret;
}


// The external interface: allocate 'n' mblocks, and return the
// address.

152
153
154
void *
getMBlocks(nat n)
{
155
  static caddr_t next_request = (caddr_t)HEAP_BASE;
156
157
  caddr_t ret;
  lnat size = MBLOCK_SIZE * n;
158
  nat i;
159
 
160
161
162
163
164
  if (next_request == 0) {
      // use gen_map_mblocks the first time.
      ret = gen_map_mblocks(size);
  } else {
      ret = my_mmap(next_request, size);
165
  
166
167
168
169
170
171
172
173
      if (ret == (void *)-1) {
	  if (errno == ENOMEM) {
	      belch("out of memory (requested %d bytes)", n * BLOCK_SIZE);
	      stg_exit(EXIT_FAILURE);
	  } else {
	      barf("getMBlock: mmap failed");
	  }
      }
174

175
176
177
178
179
180
181
182
183
184
185
186
187
      if (((W_)ret & MBLOCK_MASK) != 0) {
	  // misaligned block!
#ifdef DEBUG
	  belch("getMBlock: misaligned block %p returned when allocating %d megablock(s) at %p", ret, n, next_request);
#endif
	  
	  // unmap this block...
	  if (munmap(ret, size) == -1) {
	      barf("getMBlock: munmap failed");
	  }
	  // and do it the hard way
	  ret = gen_map_mblocks(size);
      }
188
189
  }

190
191
192
  // Next time, we'll try to allocate right after the block we just got.
  next_request = ret + size;

ken's avatar
ken committed
193
  IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at %p\n",n,ret));
194

195
196
197
198
  // fill in the table
  for (i = 0; i < n; i++) {
      mblockIsHeap( ret + i * MBLOCK_SIZE );
  }
199

200
  mblocks_allocated += n;
201

202
203
  return ret;
}
sof's avatar
sof committed
204

sof's avatar
sof committed
205
#else /* defined(mingw32_TARGET_OS) || defined(cygwin32_TARGET_OS) */
sof's avatar
sof committed
206
207
208
209
210

/*
 On Win32 platforms we make use of the two-phased virtual memory API
 to allocate mega blocks. We proceed as follows:

sof's avatar
sof committed
211
212
213
214
215
 Reserve a large chunk of VM (256M at the time, or what the user asked
 for via the -M option), but don't supply a base address that's aligned on
 a MB boundary. Instead we round up to the nearest mblock from the chunk of
 VM we're handed back from the OS (at the moment we just leave the 'slop' at
 the beginning of the reserved chunk unused - ToDo: reuse it .)
sof's avatar
sof committed
216
217

 Reserving memory doesn't allocate physical storage (not even in the
sof's avatar
sof committed
218
 page file), this is done later on by committing pages (or mega-blocks in
sof's avatar
sof committed
219
220
221
 our case).
*/

sof's avatar
sof committed
222
char* base_non_committed = (char*)0;
sof's avatar
sof committed
223
char* end_non_committed = (char*)0;
sof's avatar
sof committed
224

sof's avatar
sof committed
225
/* Default is to reserve 256M of VM to minimise the slop cost. */
226
#define SIZE_RESERVED_POOL  ( 256 * 1024 * 1024 )
sof's avatar
sof committed
227

sof's avatar
sof committed
228
229
230
/* Number of bytes reserved */
static unsigned long size_reserved_pool = SIZE_RESERVED_POOL;

sof's avatar
sof committed
231
232
233
234
235
236
237
238
void *
getMBlocks(nat n)
{
  static char* base_mblocks       = (char*)0;
  static char* next_request       = (char*)0;
  void* ret                       = (void*)0;

  lnat size = MBLOCK_SIZE * n;
sof's avatar
sof committed
239
240
241
242
243
244
245
246
247
248
249
  
  if ( (base_non_committed == 0) || (next_request + size > end_non_committed) ) {
    if (base_non_committed) {
      barf("RTS exhausted max heap size (%d bytes)\n", size_reserved_pool);
    }
    if (RtsFlags.GcFlags.maxHeapSize != 0) {
      size_reserved_pool = BLOCK_SIZE * RtsFlags.GcFlags.maxHeapSize;
      if (size_reserved_pool < MBLOCK_SIZE) {
	size_reserved_pool = 2*MBLOCK_SIZE;
      }
    }
sof's avatar
sof committed
250
    base_non_committed = VirtualAlloc ( NULL
sof's avatar
sof committed
251
                                      , size_reserved_pool
sof's avatar
sof committed
252
253
254
255
				      , MEM_RESERVE
				      , PAGE_READWRITE
				      );
    if ( base_non_committed == 0 ) {
256
         fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
sof's avatar
sof committed
257
258
         ret=(void*)-1;
    } else {
sof's avatar
sof committed
259
260
261
      end_non_committed = (char*)base_non_committed + (unsigned long)size_reserved_pool;
      /* The returned pointer is not aligned on a mega-block boundary. Make it. */
      base_mblocks = (char*)((unsigned long)base_non_committed & (unsigned long)0xfff00000) + MBLOCK_SIZE;
262
263
#      if 0
       fprintf(stderr, "getMBlocks: Dropping %d bytes off of 256M chunk\n", 
sof's avatar
sof committed
264
	               (unsigned)base_mblocks - (unsigned)base_non_committed);
265
#      endif
sof's avatar
sof committed
266

sof's avatar
sof committed
267
       if ( ((char*)base_mblocks + size) > end_non_committed ) {
268
          fprintf(stderr, "getMBlocks: oops, committed too small a region to start with.");
sof's avatar
sof committed
269
270
271
272
273
274
275
276
277
278
	  ret=(void*)-1;
       } else {
          next_request = base_mblocks;
       }
    }
  }
  /* Commit the mega block(s) to phys mem */
  if ( ret != (void*)-1 ) {
     ret = VirtualAlloc(next_request, size, MEM_COMMIT, PAGE_READWRITE);
     if (ret == NULL) {
279
        fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
sof's avatar
sof committed
280
281
282
283
284
        ret=(void*)-1;
     }
  }

  if (((W_)ret & MBLOCK_MASK) != 0) {
285
    barf("getMBlocks: misaligned block returned");
sof's avatar
sof committed
286
287
  }

288
289
290
  if (ret == (void*)-1) {
     barf("getMBlocks: unknown memory allocation failure on Win32.");
  }
sof's avatar
sof committed
291

292
  IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at 0x%x\n",n,(nat)ret));
sof's avatar
sof committed
293
294
295
296
  next_request = (char*)next_request + size;

  mblocks_allocated += n;
  
297
298
299
300
301
  // fill in the table
  for (i = 0; i < n; i++) {
      mblockIsHeap( ret + i * MBLOCK_SIZE );
  }

sof's avatar
sof committed
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
  return ret;
}

/* Hand back the physical memory that is allocated to a mega-block. 
   ToDo: chain the released mega block onto some list so that
         getMBlocks() can get at it.

   Currently unused.
*/
#if 0
void
freeMBlock(void* p, nat n)
{
  BOOL rc;

  rc = VirtualFree(p, n * MBLOCK_SIZE , MEM_DECOMMIT );
  
  if (rc == FALSE) {
320
#    ifdef DEBUG
sof's avatar
sof committed
321
     fprintf(stderr, "freeMBlocks: VirtualFree failed with: %d\n", GetLastError());
322
#    endif
sof's avatar
sof committed
323
324
325
326
327
328
  }

}
#endif

#endif